Health, Safety And Business Consequences Of Sleep Loss

Many years ago, members of our industry recognized that pilots suffering from alcoholism needed help. Leaders from the Airline Pilots Association, FAA and airline managers formed a cooperative tripartite system designed to identify, intervene, treat and obtain the medical clearance for pilots to return to work. The first version of this project was called the Human Intervention and Motivation Study (HIMS), and since then, the program has saved an untold number of pilots.

Leaders in aviation are now recognizing that a similar strategy is needed to help the many pilots who face mental health challenges. The FAA’s Mental Health and Aviation Medical Clearances Rulemaking Committee released its report on April 1, 2024, with numerous recommendations on ways to identify and break down barriers that discourage pilots from reporting and seeking care for mental health issues.

Hopefully the wide spectrum of recommendations will make a positive difference for pilots to get an accurate diagnosis, evidence-based treatment, live a higher quality of life and—except for harsh mental health symptoms—be able to enjoy a long, rewarding aviation career in the cockpit.

Recipe For Depression

Sleep loss can be a recipe for depression. With that said, the aviation profession faces an inescapable challenge which directly affects mental health. Aviation operations are conducted 24/7, often across multiple time zones. Our jobs require us to be alert when most humans are comfortably sound asleep. The potential for sleep loss is a near certainty, and it creates dire consequences on mental health.

Psychiatrist Dr Michael Freeman—clinical professor, Department of Psychiatry, University of California at San Francisco School of Medicine—sums up this vital and pervasive problem, “You take away sleep, and you’ve got a recipe for depression.”

Dr. Matthew Walker, professor of neuroscience and psychology at the University of California, Berkeley and a fellow of the National Academy of Sciences, is a foremost advocate for the importance of sleep. After reading several chapters of his book Why We Sleep, it was clear that sleep is inadequately understood and given insufficient attention by our industry.   

Healthy sleep is characterized by sufficient duration and depth, appropriate timing and regularity and the absence of sleep disturbances and interruptions. During recuperative sleep, the brain and critical systems in the body—including the immune, hormonal and cardiovascular metabolism systems—undergo important cycles necessary to maintain good physical and mental health.

A recently published study titled “Sleep Patterns of Pilots: An Objective Assessment” (conducted by Mohammed Abdelaziz, et al., published in Cureus 2023 May) utilized actigraphy (similar to a wrist watch) to objectively collect sleep evaluations on 24 pilots flying the Airbus A320. The actigraphy data revealed that 66.7% had an irregular sleep pattern and 41.7% had poor sleep efficiency. Furthermore, 12.5% exhibited daytime sleepiness, 33% had poor sleep quality and 29.2% had fatigue.

Unfortunately getting adequate sleep is not easy in our profession. A NASA Ames Research Center team led by Dr. Curtis Graeber found that the sleep deficit for a tour begins even before showing up for the first trip of a tour, especially if the report time for the trip involves an early wake-up. This means the average pilot shows up on the first day of the trip with a sleep deficit already.

NASA studies also found that the average pilot sleeps an hour less per night during layovers than at home. This source of sleep loss is due to the significantly higher number of awakenings during hotel layovers than during nights at home.

How about the quality of sleeping quarters? Statistics collected by the hotel industry reveal that noise from other guests is the number one complaint of hotel guests. Sadly, the majority of hotels are not built with soundproofing as a feature, and the number of hotels that set aside a specific “quiet zone” is scant. The quality of the sleep environment is an important contributor to rest and recovery, yet we pilots have no control over this and simply have to endure untold nights of less-than-restful sleep during our careers.   

Providing a comfortable sleep environment for crewmembers to obtain recuperative sleep needs to become a higher priority for the industry.

Sleep disruptions are more than a mere annoyance. Walker reports that sleep disruptions have serious short-term and long-term effects on our physical and mental health.  Short-term effects include increased stress response, emotional distress, mood disorders and cognitive, memory and performance deficits. Sleep disruption negatively affections a person’s attention, vigilance, emotional reactivity, memory formation, decision-making, risk-taking behavior and judgment. Other studies have found that sleep disruption interrupts the production of important chemicals in the brain and have linked this imbalance to psychiatric conditions.

Have you felt yourself getting even more tired during the progression of a multi-leg trip? This is called “sleep debt”—and it is very real.

Let us say you have the dreaded 5:00 a.m. show up on day one of a trip beginning in your crew base on the U.S. West Coast for a day’s itinerary that ends on the East Coast. Even if you attempted to try getting to sleep around 7 p.m., it is unlikely that you were able to get to fall asleep that early. More likely, you were not able to fall asleep until your normal time of 11 p.m., which means you slept only 4 hr. Any normal pilot would have felt groggy all day long.

Upon getting to the East Coast, let us assume that the scheduler notifies you that tomorrow’s departure will be at 7:00 a.m., meaning that you need to be at the FBO by 5:30 a.m. the next morning. At 9:00 p.m. local (which is only 6 p.m. according to your body’s circadian rhythm) you grimace as you look at the alarm clock to make certain it is properly set for 4:00 a.m. Will you be able to drop immediately into deep restful sleep? Not likely.

According to Graeber, when sleep is attempted at a time abnormal to a person's circadian rhythm, the crewmember will have considerably more difficulty getting to sleep and, if successful, will usually awaken within a relatively short time. Basically stated, most people get their normal recuperative rest when they go to sleep at their regular time and wake up at their typical time. Doing otherwise substantially cuts down on the quality and quantity of sleep. We cannot simply “switch ourselves into deep sleep” just because the crew schedulers tells us this is our 10-hr. rest period. It is the timing of sleep, not the amount of time awake or "in rest," that is the critical factor controlling sleep quality.

How much deep recuperative sleep did you manage to get that night when the alarm clock jolted you awake, which—by the way—occurred at 1 a.m. on your body clock? Clearly not enough. Perhaps it was 4 hr. of deep sleep. Remember that you had 4 hr. of sleep debt from the night before the tour. This second night adds another 4 hr. of sleep deficit. By the start of day two, you already have accumulated 8 hr. of sleep debt. That is the equivalent of missing an entire night of sleep.    

Changing time zones or operating on the “back side of the clock” imposes the additional burden of circadian desynchronization. Graeber’s research found that the circadian rhythm system is unable to adjust rapidly to sudden shifts. In effect, the system resists changes in its timing and stability. Consequently, complete resynchronization of the biological timing system can often take several days.

Battle To Recover

Walker’s research found that people do not realize how sleep deprived they actually are. Our own subjective senses are miserable measurements of our sleep loss. Once a human gets below 7 hr. of high-quality sleep, objective measurements reveal the significant impairments in a person’s body and brain.

There are substantial differences in the ability of individuals to adjust their rhythms to repeated time-zone shifts. Some people adapt more easily than others. “Morning people,” introverted persons, older persons and persons with stable rhythms have slower rates of resynchronization than their counterparts. Age is another factor working against our ability to obtain quality sleep. The studies found that older crewmembers (greater than 45-50 years old) experience less total sleep as well as poorer-quality sleep.

The combination of poor sleep quality on the road as well as trying to sleep at times outside of your body’s normal sleep window will worsen the sleep debt during a trip. NASA research found that air crews tend to accumulate more sleep debt and thus became more fatigued as they progressed through a trip.

Dr David Gozal, a professor at the University of Chicago School of Medicine specializing in sleep disorders and deputy editor of the journal Sleep and Frontiers in Neurology, found that recovery from sleep loss does not immediately restore all of the body’s systems. He cautions about sleep loss by using the analogy of a bank account. “If you accumulate debt, there will be compounded interest and an uphill battle to recover.”

Walker’s research raises concerns about those who frequently experience sleep loss, and this point particularly applies to pilots and ATC controllers. When a person begins to experience insufficient sleep, they begin to lower their baseline expectations of their health and wellness. A person will begin to justify “this is just where I am in life.”

A study from the Department of Psychology at the University of Durham (Cho Kei, Ennaceur A, Cole JC, Suh CK. “Chronic Jet Lag Produces Cognitive Deficits.” Journal of Neuroscience. 2000 Mar 15;20[6]) found that crewmembers exhibited cognitive deficits, possibly in working memory, which became apparent after several years of chronic disruption of circadian rhythms.

Stressful days in the cockpit with high cognitive and emotional demands increase sleep problems. A study of the entire population of HEMS pilots in the Netherlands (Mirjam Radstaak, Sabine AEG, Debby GJB, Jos FB, Michiel AJK. “Work Stressors, Perseverative Cognition and Objective Sleep Quality: A Longitudinal Study among Dutch HEMS Pilots.” Journal of Occupational Health. 2014;56:469-477) found distressing shifts to be associated with a longer time to fall asleep. High workload shifts were associated with poorer sleep quality, a longer time to fall asleep and shorter total sleep time. The study also found it is harder to recover from a distressing shift than from a busy shift. The possible explanation is that distressing shifts are more emotionally charged than high-workload shifts.

Career Survival

According to Walker, sleep is probably the greatest “performance-enhancing drug” you could wish for. Healthy sleep habits can make a big difference in one’s quality of life. When a person prioritizes sleep, they are likely to get more out of life. And epidemiologic studies have even shown that those who sleep less are statistically more likely to have a shorter life.

The National Institutes of Health published tips for getting a good night’s sleep. One of the prime recommendations is to stick to a sleep schedule on the same bedtime and wake-up time, even on the weekends. This helps to regulate the body’s clock and aids falling asleep. While this is sage advice backed up by considerable medical research, it unfortunately is nearly impossible for most pilots, ATC controllers and anyone working variable work schedules.

Another important suggestion is to practice a relaxing routine before bedtime away from bright lights. This helps to separate one’s sleep time from activities that can cause excitement, stress or anxiety, all of which make it more difficult to fall asleep, get deep sleep or remain asleep. Two hours of iPad use at maximum brightness prior to bedtime suppress a person’s normal release of melatonin, a vital hormone which tells the body it is nighttime and helps us go to sleep, according to Marianna Figueiro of the Lighting Research Center at Rensselaer Polytechnic Institute and her team. Suppressing melatonin means delaying sleep. If this is done chronically, it can lead to disruption of the circadian system, possibly leading to serious health consequences.

In terms of getting better sleep at night, taking a “power nap,” especially in the afternoon, is to be avoided as it can cause difficulty falling asleep later. Avoid napping past 3 p.m.

Vigorous exercise should be done no closer to bedtime than 6 hr., and mild exercise should be done no later than 2-3 hr. before bedtime. Do flight crewmembers have total control over this while out on the road? No.

The risk of sleep apnea rises markedly with weight, and staying in shape is an effective means to avoid that problem. When possible, an exercise regime is going to have multiple positive effects on your physical and mental health. Fortunately, the diagnosis and treatment of sleep apnea is well understood by the aeromedical profession, and pilots who have been treated for sleep apnea have reported immense improvements in their physical and mental health.

The next suggestion is going to be tough for those of us who belong to the “Isn’t coffee one of the essential food groups?” club. Coffee, colas, some teas and chocolate (especially the dark varieties) contain caffeine, which is a stimulant.  It can take as long as 8 hr. for the effects of caffeine to wear off.   

Nicotine is also a stimulant that causes smokers to sleep lightly. Smokers also tend to wake up too early due to nicotine withdrawal. This is one of many reasons from the healthcare industry to avoid nicotine in any form.

Another factor the pilot can control is the food and liquid consumption for the evening meal. Even if you have the legal “bottle to throttle” time before your next duty period, an evening nightcap results in less sound sleep and waking up more tired. Alcohol suppresses the rapid eye movement phase of sleep. And while a big dinner may be a nice way to wind down after a tough day of flying, the prolonged digestion interferes with a good night’s sleep.

“Road warriors” will realize the difficulty of adhering to the next suggestion. It recommends establishing a comfortable sleep environment, preferably cool (60F-67F), and the bedroom should be free from any light. One hotel near a major UPS hub that provided a dedicated floor for flight crewmembers did have windows equipped with two layers of blackout curtains, which is ideal.

Fellow road warriors have learned a few tricks to try creating a better sleep environment. Eye shades, ear plugs, white-noise machines, humidifiers and fans can help create a more comfortable sleep environment. A relaxing activity, such as reading or listening to music, should become part of a bedtime ritual.

A hot bath or shower before bed can help with relaxation, and the drop in body temperature can help a person feel sleepy.   

Try to get outside in natural sunlight for at least 30 min. each day, then turn down the lights before bedtime. The National Institutes of Health recommendations include waking up with the sunrise, which is yet another tip that simply is not doable for the majority of aviation schedules.

Adherence to the factors you can control—diet, weight, exercise when possible and avoiding television and laptops prior to sleep—are relatively effective factors to improve your sleep, and possibly allow you to continue a long flying career.